Analysis
First lets look at the genres of each playlist
Main genres
As you can see, there is a clear difference between the two
playlists. The long-distance playlist contains mostly pop songs, unlike
the sprinters playlist, which mainly consists of rock songs.
Pop music is a genre that is often regarded as a softer alternative
to rock. Pop involves more singing and vocal expression, with a
danceable beat to it. Rock on the other hand is played on loud sounds of
instruments and is high in energy.
In the following tabs of the analysis, we will dive deeper into the
different playlist. Are there indeed noticeable differences in energy or
danceability for example? Furthermore, we will explore individual songs
that stand out in the data.
Changes in energy and danceability
point out the differences between sprinters and long-distance
swimmers
As the plots show, sprinters listen to music with higher energy, and
the songs of long-distance swimmers have higher danceability.
One outlier in energy is the song “Nothing else matters” from
Metallica. This song is 0.41 lower in energy than the median of the
long-distance playlist. The expectation was that mostly high energy
songs are played before the race. So why is this particular song, with
relatively low energy, still in the long distance playlist? One
explanation could be that people listen to this song because they want
to control their nerves before the race and don’t want to listen to a
very energetic song. The lyrics of the song could also play an important
role. The song “Nothing else matters”, is about being honest with your
feelings and expressing them. Putting yourself out there and take a
risk. I can imagine that one could get more confidence from this
song.
Danceability describes how suitable a song is for dancing. This is
based on a combination of different musical elements, including temo,
rithmstability and beat strength. If a track has 0 danceability, it is
least danceable, and a danceability of 1.0 means it is most danceable.
The median of the long-distance playlist is 0.70, which is higher than
the median of 0,51 from the sprinters playlist.
In the sprinters playlist, there is one outlier. The track “Moth Into
Flame” from Metallica has a very low danceability of 0.16. On the other
hand, the track has a very high energy of 0.98. Listening to the song
makes me understand why a sprinter would listen to it right before a
race. During a race, sprinters have a relatively high arm frequency
(number of strokes you make per minute). Therefore, a track that is high
in energy and tempo could help to get into the right state of mind.
Lets look at the tempo. Do sprinters listen to
tracks with a higher tempo?
The tempo histogram shows the tempi of the two playlists. We can see
that the mean tempo of the sprinters playlist is 138.6 BPM and the mean
tempo of the long-distance playlist is 120.9 BPM. That the tempo of the
playlist for sprinters is higher than that of the long-distance playlist
is in line with our expectations. Given that the two main genres, Rock
and Metal, usually have a higher tempo than pop and Hip Hop music:
| Pop |
100-130 |
| Rock |
110-140 |
| Metal |
100-160 |
| Hip Hop |
85-115 |
Looking at the histogram, only two tracks from the sprinters playlist
have a tempo below 100 BPM. This are the tracks “Basket Case” and “Eyes
of a panther”. Especially the last one is interesting. According to
Spotify, this track has a BPM of 88.6. However, if you listen to it, it
doesn’t seem to have such a low tempo. In the next tab, we will look at
a tempogram of this song to figure out what is happening.
Diving deeper into “Eyes of a panther” from Steel Panther by looking
at tempograms

Tempo is the speed or pace of music. It is usually described in beats
per minute (BPM), or how many pulses per minute. A tempogram can be used
as an indicator of the local relevance of a specific tempo for a
specific track for each time instance. The plots at the left show a
Fourier-based tempogram that attempts to use Spotify’s API to analyse
the tempo of two songs: Eyes of a Panther, and Lease On Life. Overall,
Spotify estimates that the tempo of both tracks are 88 BPM. However,
when we listen to both songs, they sound very different. When we look at
the tempograms of both songs, we can see that there is a bright yellow
line around 90 BPM. Nonetheless, there is a difference between the two
tempograms. The tempogram of Eyes of a Panther, also has bright yellow
spots all over the tempogram, instead of just at 90 BPM. This could
indicate that tempo estimation is extremely hard for this song. In
contrast to Lease On Life, where the tempogram is mainly dark blue, and
only shows a yellow color at 90BPM, which matches the estimated tempo
Spotify gave us.
If we summarize the tempo,
duration and volume features, is there
a clear difference between the playlists?

Summarizing low level track features like duration, volume and tempo
results in the plot on the left. At first it might seem that this plot
only shows a lot of points. However, there are some interesting
observations to make.
First, if we look at the size of the points, we can see that the
points of the long-distance playlist are a bit larger than the points of
the sprinters playlist. This means that in general the duration of the
tracks of the long-distance playlist are longer. The longest track of
the long-distance playlist 410sec and the shortest track is 158sec. This
differs for the sprinters playlist, where the longest track is 350sec
and the shortest only 90sec.
Furthermore, comparing the overall volume of the two playlists, both
playlists do not seem to differ very much. The average volume of both
playlists are almost identical, namely -5.3 dBFS.